Field of the Invention
This invention relates to a swivel truck for rail vehicles, especially for streetcars, which is capable of pivoting to such an extent that curves of even small radius can be negotiated.
This invention is particularly concerned with a swivel truck for rail vehicles which is flexible, i.e., a truck in which, when one of the wheel axis bearings or one of the contact points between the wheels and the rails is lifted out of the plane of the other three axle bearings or contact points, the contact pressures do not become any higher than is permitted in the case of vehicles having sprung axle bearings.
This invention is particularly directed to a swivel truck for a rail vehicle having a swivel truck frame of longitudinal members and cross members wherein the longitudinal members are of an underslung configuration in a central portion thereof and the cross members are connected to a middle portion thereof as by welding to provide a balancing of the wheel loads within the swivel truck by deformation of the swivel truck frame independently from any spring constants of a springing system therein. The construction of the swivel truck of the present invention permits the entire truck to undergo torsion, i.e., it allows for the situation that if one end of the one of the longitudinal members of the swivel truck frame is lifted up while the other three ends remain constant no great reaction of forces occurs.
This invention further relates to a flexible motor-powered swivel truck in which the motor is resiliently suspended and a resilient torque coupling is inserted into the drive between the motor shaft and the wheel axle. The invention is further directed to a swivel truck in which there is a cradle frame supported on a swivel truck frame by means of at least one coil spring, preferably a pair of coil springs disposed between the swivel truck frame and the cradle frame. Particularly contemplated is a swivel truck wherein a pair of coil springs are employed, each pair of coil springs being provided with an additional supplementary spring of rubber or or material disposed between each of the coil springs and the cradle frame. Especially contemplated is a supplementary spring of rubber or rubber elastic material disposed within each of the coil springs of the spring system.
The invention also relates to a motorized swivel. truck in which the longitudinal truck frame members are of a specific underslung configuration between the points at which the cross-members are welded, and the cross-members are of an arched configuration, the motor being suspended from the cross members and additionally from the longitudinal members.